I agree that designer labels are normally over-priced; however, they are not always bad quality.
The designer fusion lines tend to be bad quality - I cannot comment on the currently quality of mainline Dolce & Gabbana suits; going back 3/4 years ago, there were very good quality and underrated.

The Gieves & Hawskes rtw model, was to try everything - half-canvas suits, some fused jackets, Gieves fusion line, blazer shop and casual wear. They should have kept it simple with a decent half-canvas product; instead, it seems they are were targeting too many things.
They become 'lost' and this had a negative impact; hence, the closure of a lot concessions.
The shop space on Savile Row has seen so many changes, as they try different things.

I would recommend Cad & The Dandy, I have had a number of garments from them: two-piece suit, tweed jacket and three odd-trousers; with another two odd-trousers to follow.
They even did a good job on some alterations for me.
I did try someone above the Cad & The Dandy price bracket, but below Savile Row, at the end of last year. Not the process or final product, someone would expect for the price.
Every tailor in the world, will have at least one unhappy customer....

Suede is good starting point, even if black suede oxfords - light/medium/dark brown and oxblood/burgundy would be better options
Colour - lighter colours work well for a casual look, i.e light brown; white/baby-blue in the summer
Pattern can make a difference, I have a pair of Cheaney's for Gieves & Hawkes, which has a herringbone style pattern that I wear with chinos. Lodger once did an oxford with linen uppers.

Mid-grey
You can get away with it as most business meetings (depending on your field), wear outside of work with it looking like a work suit and depending on cloth, you can wear it as a summer suit too.